A method and system for measuring multi-dimensional combustion gas temperature and multi-component concentration in a furnace

Abstract

The present invention relates to a method and system for measuring the temperature and multi-component concentration of multi-dimensional combustion gas in a furnace. A laser emits m first lasers; an optical switch couples the m first lasers into one laser, and controls each laser to output alternately according to a preset time sequence; a spectrometer divides each laser into 2np lasers; the 2np lasers pass through the combustion gas, and each component in the gas to be measured absorbs the first laser with a corresponding central wavelength; the m first lasers that are not completely absorbed pass through the combustion gas in a time sequence, and each first laser forms 2np second lasers; a photoelectric converter performs photoelectric conversion on the second laser in a time sequence, and each 2np second laser forms 2np electrical signals; a phase-locked amplifier processes the electrical signal, and sequentially generates m×2np second harmonic signals in a time sequence; a host computer processes the sequentially generated second harmonic signals to obtain the multi-dimensional combustion gas temperature and multi-component concentration.

Description

Technical Field

[0001] The invention relates to the field of non-contact gas measurement, and in particular to a method and system for measuring multi-dimensional combustion gas temperature and multi-component concentration in a furnace. Background Art

[0002] Boilers are energy output devices in thermal power plants, and the furnace involves a complex combustion process. The measurement of combustion parameters in the furnace is of positive significance for studying the combustion mechanism, improving combustion efficiency, and controlling pollutant emissions. Combustion temperature and component concentration are the most basic combustion parameters in the furnace. Conventional measurement methods such as thermocouples and flue gas analyzers are single-point measurements, but single-point measurements can only reflect the overall combustion conditions in the furnace and cannot reflect the local combustion conditions in the furnace. Since single-point measurement makes it difficult to monitor whether the flame center in the furnace deviates, it causes problems such as reduced boiler efficiency, increased pollutant emissions, high-temperature corrosion of the water-cooled wall, and severe slagging. In addition, conventional contact measurement methods such as thermocouples and flue gas analyzers cannot adapt to the high-temperature, dusty and turbulent furnace environment for a long time.

[0003] Laser combustion diagnostic technology is an online non-contact measurement method that can achieve fast and non-interference measurement of combustion parameters. Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology has the advantages of simple system structure, high precision, fast response and strong environmental adaptability. Traditional TDLAS technology measures the integrated absorbance of a component along the optical path in the measured area, thereby inverting the average temperature and component concentration on the optical path. Since the actual furnace is a three-dimensional structure, the temperature and component concentration distribution of the combustion gas in the furnace vary greatly. At present, the measurement of temperature and component concentration based on TDLAS technology is mainly limited to the laboratory level, and there is no application in actual boilers. In addition, the existing TDLAS technology cannot meet the simultaneous online measurement of combustion gas temperature and multiple component concentrations.

[0004] Therefore, how to provide a method or system that can simultaneously measure the multi-dimensional combustion gas temperature and multi-component concentration in the furnace online has become a demand of the prior art. Summary of the invention

[0005] The present invention provides a method and system for measuring the multi-dimensional combustion gas temperature and multi-component concentration in a furnace, so as to solve the technical problem that the existing measuring device cannot measure the three-dimensional temperature and component concentration of the combustion gas.

[0006] In a first aspect, the present invention provides a method for measuring the temperature and multi-component concentration of a multi-dimensional combustion gas in a furnace, the method comprising: a laser emits m first lasers, wherein 1≤m≤M, and M is the number of gas components to be measured; the wavelengths of the m first lasers respectively cover the molecular absorption spectrum ranges of the gas components to be measured; an optical switch couples the m first lasers into one laser path, and controls each of the m first lasers to be output alternately at a preset time sequence; a spectrometer divides each of the m first lasers output alternately at a preset time sequence into 2np laser paths, where n and p are both positive integers; the 2np laser paths pass through the combustion gas, 2np lasers form a p-layer n×n optical path grid, each component in the gas to be measured absorbs the first laser with the corresponding central wavelength; m types of first lasers that are not completely absorbed pass through the combustion gas in a time sequence, and each first laser forms 2np second lasers; the photoelectric converter performs photoelectric conversion on the m types of 2np second lasers in a time sequence, and each 2np second laser forms 2np electrical signals; the phase-locked amplifier processes the electrical signals formed in sequence, and generates m×2np second harmonic signals in sequence; the host computer processes the m×2np second harmonic signals generated in sequence to obtain multi-dimensional combustion gas temperature and multi-component concentration.

[0007] In a second aspect, the present invention further provides a furnace multi-dimensional combustion gas temperature and multi-component concentration measurement system, characterized in that: the furnace multi-dimensional combustion gas temperature and multi-component concentration measurement system comprises a host computer, a laser, an optical switch, a spectrometer, a photoelectric converter, a phase-locked amplifier and an acquisition card; the laser is electrically connected to the host computer, and the laser emits m kinds of first lasers, wherein 1≤m≤M, and M is the number of gas components to be measured; the wavelengths of the m kinds of first lasers respectively cover the molecular absorption spectrum ranges of the gas components to be measured; the optical switch is connected to the laser, and the optical switch is also electrically connected to the host computer, and the optical switch couples the m kinds of first lasers into one laser, and controls each of the m kinds of first lasers to be output alternately according to a preset timing; the spectrometer is connected to the optical switch, and the spectrometer divides each of the m kinds of first lasers output alternately according to a preset timing into 2np lasers, where n and p are both positive integers; the 2np lasers pass through the combustion gas, and the 2np lasers form p The invention discloses an n×n optical path grid, wherein each component in the gas to be measured absorbs the first laser with the corresponding central wavelength; the m first lasers that are not completely absorbed pass through the combustion gas in sequence, and each first laser forms 2np second lasers; the photoelectric converter is used to perform photoelectric conversion on the m 2np second lasers in sequence, and each 2np second lasers forms 2np electrical signals; the acquisition card is electrically connected to the photoelectric converter, and the acquisition card acquires the electrical signals formed by the photoelectric conversion of the m 2np second lasers in sequence and converts them into digital signals for transmission to the lock-in amplifier; the lock-in amplifier is electrically connected to the acquisition card, and the lock-in amplifier is also electrically connected to the host computer, and the lock-in amplifier processes the digital signals formed in sequence in sequence, and generates m×2np second harmonic signals in sequence in sequence; the host computer is used to process the m×2np second harmonic signals generated in sequence to obtain the multi-dimensional combustion gas temperature and multi-component concentration.

[0008] Compared with the prior art, the present invention provides a method and system for measuring the temperature and multi-component concentration of multi-dimensional combustion gas in a furnace, wherein a laser emits m first lasers, wherein 1≤m≤M, and M is the number of gas components to be measured; the wavelength bands of the m first lasers respectively cover the molecular absorption spectrum ranges of the gas components to be measured; an optical switch couples the m first lasers into one laser path, and controls each of the m first lasers to be alternately output according to a preset time sequence; a spectrometer divides each of the m first lasers alternately output according to a preset time sequence into 2np laser paths, where n and p are both positive integers; the 2np laser paths pass through the combustion gas, and the 2np laser paths form a p-layer n×n optical path grid, and each component in the gas to be measured absorbs the first laser of the corresponding central wavelength; the m first lasers that are not completely absorbed pass through the combustion gas in time sequence, and each first laser forms a 2np second laser path; the photoelectric converter is arranged according to The m types of 2np second lasers are photoelectrically converted in sequence, and each 2np second laser forms 2np electrical signals; the phase-locked amplifier processes the electrical signals formed in sequence, and generates m×2np second harmonic signals in sequence; the host computer processes the m×2np second harmonic signals generated in sequence to obtain the multi-dimensional combustion gas temperature and multi-component concentration, and realizes the measurement of multi-dimensional combustion gas temperature and multi-component concentration in the furnace. For the high-temperature and harsh furnace environment, the non-contact online measurement of multi-dimensional combustion gas temperature and multi-component concentration in the furnace is realized based on the TDLAS technology, which has the advantages of no interference, high precision, fast response speed and strong adaptability to the environment; the optical switch technology, as a time-sharing measurement technology, realizes the simultaneous measurement of multiple combustion parameters and eliminates the mutual interference between multi-component gases, and the spectrometer technology realizes the measurement of multi-dimensional combustion parameter fields, simplifies the system structure and saves equipment costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 Schematic diagram of the flow of the method for measuring the temperature and multi-component concentration of multi-dimensional combustion gas in a furnace according to the first embodiment of the present invention.

[0010] Figure 2 Schematic diagram of the structure of a p-layer n×n optical path grid formed by 2np-path lasers in the first embodiment of the present invention.

[0011] Figure 3 Schematic diagram of the flow of a method for measuring multi-dimensional combustion gas temperature and multi-component concentration in a furnace according to the second embodiment of the present invention.

[0012] Figure 4 Schematic diagram of the flow of a method for measuring the temperature and multi-component concentration of multi-dimensional combustion gases in a furnace according to the third embodiment of the present invention.

[0013] Figure 5 Schematic diagram of the flow of a method for measuring the temperature and multi-component concentration of multi-dimensional combustion gases in a furnace according to the fourth embodiment of the present invention.

[0014] Figure 6 This is a schematic diagram of the module structure of a system for measuring the temperature and multi-component concentration of multi-dimensional combustion gases in a furnace according to a fifth embodiment of the present invention. DETAILED DESCRIPTION

[0015] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only the parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0016] It should be mentioned before discussing the exemplary embodiments in more detail that some exemplary embodiments are described as processes or methods depicted as flow charts. Although the flow charts describe the steps as sequential processes, many of the steps therein can be implemented in parallel, concurrently or simultaneously. In addition, the order of the steps can be rearranged. The process can be terminated when its operation is completed, but can also have additional steps not included in the accompanying drawings. The process can correspond to a method, function, procedure, subroutine, subprogram, etc.

[0017] In the description of the present invention, it is to be understood that the terms "first", "second", etc. can be used in this article to describe various directions, actions, steps or elements, but these directions, actions, steps or elements are not limited by these terms. These terms are only used to distinguish a first direction, action, step or element from another direction, action, step or element. For example, without departing from the scope of the present invention, the first speed difference can be referred to as the second speed difference, and similarly, the second speed difference can be referred to as the first speed difference. Both the first speed difference and the second speed difference are speed differences, but they are not the same speed difference. The terms "first", "second", etc. cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "many" is at least two, for example, a plurality of two, three, etc., unless otherwise clearly and specifically defined.

[0018] Please also read Figure 1 and Figure 2 The first embodiment of the present invention provides a method for measuring the temperature and multi-component concentration of multi-dimensional combustion gas in a furnace, which is used to measure the temperature of multi-dimensional combustion gas in a boiler and the concentration of the components of the gas to be measured in the combustion gas. The method for measuring the temperature and multi-component concentration of multi-dimensional combustion gas in a furnace includes:

[0019] S1: The laser emits m first lasers, wherein 1≤m≤M, and M is the number of gas components to be measured; the wavelengths of the m first lasers respectively cover the molecular absorption spectral line ranges of the gas components to be measured;

[0020] S2: The optical switch couples the m first lasers into one laser and controls each of the m first lasers to output alternately according to a preset timing;

[0021] S3: The beam splitter divides each of the m first lasers output alternately in a preset time sequence into 2np lasers, where n and p are both positive integers;

[0022] S4: 2np lasers pass through the combustion gas, and the 2np lasers form a p-layer n×n optical path grid. Each component in the gas to be measured absorbs the first laser with the corresponding central wavelength; the m first lasers that are not completely absorbed pass through the combustion gas in sequence, and each first laser forms a 2np second laser.

[0023] S5: the photoelectric converter performs photoelectric conversion on the m types of 2np second lasers in a time sequence, and each 2np second laser forms 2np electrical signals;

[0024] S6: The lock-in amplifier processes the electrical signal formed in sequence in time, and generates m×2np second harmonic signals in sequence in time;

[0025] S7: The host computer processes the m×2np second harmonic signals generated sequentially to obtain the multi-dimensional combustion gas temperature and multi-component concentration.

[0026] In S1, the number of lasers is m, and each laser emits a first laser. Each first laser is used to measure at least one gas component. For example, only the same first laser is needed to measure CO and CO2, while another first laser is needed to measure NO. m≥1, preferably, m≥2. Both m and M are positive integers. The specific number m of lasers is not limited, and it is limited by the number of gas types to be measured. In this embodiment, m=3, and the gas components to be measured in this embodiment include H2O, CO, CO2 and NO; corresponding to H2O, the central wavelength range of the first laser is 1393.8nm~1401.8nm, preferably 1397.8nm, to obtain a wavelength of 7153.75cm -1 and 7154.35cm -1 Corresponding to CO and CO2, the central wavelength range of the first laser is 1575nm~1563nm, preferably 1759nm, to obtain 6338.59cm -1 The CO absorption line at 6337.99 cm -1Corresponding to NO, the central wavelength range of the first laser is 5259nm~5267nm, preferably 5263nm, to obtain 1900.07cm -1 NO absorption line at .

[0027] In S2, an optical switch is an optical device having one or more optional transmission ports, and its function is to physically switch or logically operate an optical signal in an optical transmission line or an integrated optical circuit. Each of the m first lasers is output alternately in sequence according to a preset timing, that is, within one output cycle of the first laser, each of the m lasers must be output once. In this embodiment, the preset timing is not limited. For example, when m=3, the first laser includes A laser, B laser and C laser. Within one cycle, A laser, B laser and C laser can be output in sequence, or B laser, A laser and C laser can be output in sequence, or C laser, A laser and B laser can be output in sequence. It can be understood that there are more than the above three ways to output the three lasers alternately according to the preset timing, and they will not be listed one by one in this application.

[0028] In S3, the optical splitter is a passive device, also known as an optical splitter, which does not require external energy. As long as there is one light input, the light can be divided into multiple light paths. n is a positive integer, and the number of n is not limited. Preferably, n≥2. If the optical switch outputs A laser in the first time period, outputs B laser in the second time period, and outputs C laser in the third time period, then the optical splitter divides A laser into 2np lasers in the first time period, divides B laser into 2np lasers in the second time period, and divides C laser into 2np lasers in the third time period. 2np lasers are 2×n×p lasers. p is a positive integer, p≥1, preferably, p≥2, such as p is 3, 4 or 5, etc.

[0029] In S4, 2np lasers form a p-layer n×n optical path grid to pass through the combustion gas, that is, the beam splitter divides each of the m first lasers output alternately according to the preset timing into 2np lasers, and the 2np lasers include a first part of np lasers and a second part of np lasers, and the lasers in the first part of np lasers are parallel to each other, and the lasers in the second part of np lasers are parallel to each other; the first part of np lasers and the second part of np lasers are perpendicular to each other. Each 2n lasers form an n×n optical path grid in the same plane, and in the 2n lasers in the same plane, n lasers are perpendicular to the other n lasers. When the frequency of the 2np lasers just meets the natural vibration frequency of the gas molecules of the gas component to be measured, the photons of the first laser resonate with the gas molecules of the gas component to be measured, causing the internal dipole moment of the gas molecules to be measured to change, resulting in the photons being absorbed by the gas molecules, and the remaining lasers pass through the combustion gas to become the second laser. Since the m first lasers are output alternately according to the preset timing, there is only one 2np second laser when passing through the combustion gas in one timing. The combustion gas can be a high-temperature combustion gas inside a boiler, a gas turbine or an internal combustion engine. It can be understood that when the 2np lasers output by the spectrometer enter the combustion gas, a certain device can be used, such as using a single-mode optical fiber to make each of the 2np lasers emit from a preset position and angle. When p=1, the present invention measures the combustion gas in the same plane, that is, the two-dimensional combustion gas temperature and multi-component concentration; when p≥2, the present invention measures the combustion gas in multiple planes, that is, the combustion gas in the 1st layer, the i-th layer to the p-th layer, 1≤i≤p, i is a positive integer, so that the multi-dimensional combustion gas temperature and multi-component concentration can be measured.

[0030] In S5, the photoelectric converters include 2np, each of which converts one second laser beam. Since m types of 2np second laser beams alternately pass through the combustion gas according to a preset time sequence, only one type of 2np second laser beam passes through the combustion gas in one time sequence, and the 2np photoelectric converters only receive 2np laser beams in one time sequence and form 2np electrical signals, and m×2np electrical signals are sequentially formed in one output cycle of the first laser beam.

[0031] In S6, the phase-locked amplifier is used for low-pass filtering, weak signal extraction and harmonic detection to complete the acquisition and processing of the second harmonic. The phase-locked amplifier only needs to process 2np electrical signals in one time sequence. In one output cycle of the first laser, the phase-locked amplifier processes the m×2np electrical signals formed in sequence and generates m×2np second harmonic signals in sequence.

[0032] In S7, the host computer obtains the multi-dimensional combustion gas temperature and multi-component concentration based on the TDLAS measurement principle and algebraic iteration algorithm.

[0033] TDLAS measurement principle

[0034] The Beer-Lambert law is expressed as follows: Assuming that a laser beam with a frequency of v passes through the area of ​​the gas to be measured and is absorbed by the uniform medium of the gas to be measured, the integrated absorbance A on the optical path is:

[0035] A=∫ v A v (v)dv=∫ v -ln(I t / I0)dv=P·X·S(T)L=α v L (1)

[0036] Where: A is the integrated absorbance on the light path; A ν is absorbance; I0 and I t are the incident light intensity and the transmitted light intensity respectively; P is the total pressure of the mixed gas; X is the concentration of the medium gas component; L is the transmission distance of the laser path in the medium gas; S is the absorption line intensity; T is the temperature; α v is the gas absorption coefficient.

[0037] Under the condition of thermal equilibrium system, the spectral line intensity S(T) at temperature T is:

[0038]

[0039] Where: S(T0) is the spectral line intensity at the reference temperature T0; E is the low-state energy level value; h is the Planck constant; k is the Boltzmann constant; c is the speed of light; ν0 is the center frequency of the absorption spectrum.

[0040] Q(T) is the partition function value at temperature T and can be expressed as:

[0041] Q(T)=z0+z1T+z2T 2 +z3T 3 (3)

[0042] In the dual-line temperature measurement method of TDLAS, two absorption lines of the same gas molecule are selected, and the two absorption line intensities are divided to eliminate the partition function, and the ratio R of the intensities of different absorption lines is obtained as:

[0043]

[0044] Then the temperature T of the area to be measured can be expressed as follows through equations (2) and (4):

[0045]

[0046] After obtaining the temperature T, the spectrum line with larger absorption is generally selected to calculate the medium gas component concentration X as:

[0047]

[0048] Algebraic Iteration Algorithm

[0049] The Algebraic Reconstruction Technique (ART) is a typical CT algorithm. When performing two-dimensional reconstruction of the area to be measured, the area to be measured is divided into n×n grid cells, and it is assumed that the measured values ​​in the grid cells are evenly distributed. The integral absorption rate of a single light path can be expressed as the sum of the contributions of all the grids that the light path passes through to the absorption:

[0050]

[0051] Where i is the ray number; j is the grid number; L j It represents the optical path through the jth grid; J is the total number of grids; a is the integrated absorption coefficient within the grid.

[0052] Based on the ART algorithm, the iterative calculation formula of the absorption coefficient of the grid unit is:

[0053]

[0054] In the formula, k is the number of iterations; A i represents the integrated absorption rate of the i-th ray; β is the relaxation coefficient, L ij The optical path of the i-th ray passing through the j-th grid.

[0055] The absorption coefficient α of spectral lines v1 and v2 is obtained using the modified ART algorithm ν1,i and α ν2,i , and calculate the ratio R of the absorption line intensity in each grid i :

[0056] R i =a v1,i / a v2,i (9)

[0057] Calculate the temperature T of the grid cell using formula (5): i The spectral line intensity S of spectral lines v1 and v2 is obtained by formula (2): ν1,i (T i ) and S ν2,i (T i ), and the corresponding gas component concentration X of the grid unit is calculated by formula (6) v1,i and X v2,i .

[0058] According to the above expression, the multi-dimensional combustion gas temperature and the concentration of the gas component to be measured can be inverted. According to the second harmonic signal corresponding to the double absorption line gas, the gas temperature and component concentration corresponding to the signal can be inverted; according to the second harmonic signal corresponding to the single absorption line gas, the gas component concentration corresponding to the signal can be inverted. The temperature of the gas to be measured is inverted using the double absorption line gas; the concentration of the gas to be measured is inverted using the single / double absorption line gas.

[0059] Preferably, the gas component to be measured includes H2O, and the gas component to be measured further includes at least one of CO, CO2 and NO, and the temperature of the gas to be measured is inverted using the double absorption spectrum of H2O.

[0060] This method simultaneously inverts the temperature of the p-layer combustion gas and the concentration of multiple components, thereby reconstructing the multi-dimensional combustion gas temperature and multi-component concentration. The host computer, laser, optical switch, photoelectric converter, phase-locked amplifier and other components used in this method can all be selected from components sold on the market. This method is simple and easy to implement to measure gas temperature and multi-component concentration.

[0061] See also Figure 3 The second embodiment of the present invention also provides a method for measuring the temperature and multi-component concentration of multi-dimensional combustion gas in a furnace, the method comprising:

[0062] S01: The signal generator outputs a control signal to the laser controller so that the laser controller controls the laser. The signal generator also sends a reference signal to the lock-in amplifier;

[0063] S1: The laser emits m first lasers, wherein 1≤m≤M, and M is the number of gas components to be measured; the wavelengths of the m first lasers respectively cover the molecular absorption spectral line ranges of the gas components to be measured;

[0064] S2: The optical switch couples the m first lasers into one laser and controls each of the m first lasers to output alternately according to a preset timing;

[0065] S3: The beam splitter divides each of the m first lasers output alternately in a preset time sequence into 2np lasers, where n and p are both positive integers;

[0066] S4: 2np lasers pass through the combustion gas, and the 2np lasers form a p-layer n×n optical path grid. Each component in the gas to be measured absorbs the first laser with the corresponding central wavelength; the m first lasers that are not completely absorbed pass through the combustion gas in sequence, and each first laser forms a 2np second laser.

[0067] S5: the photoelectric converter performs photoelectric conversion on the m types of 2np second lasers in a time sequence, and each 2np second laser forms 2np electrical signals;

[0068] S6': The phase-locked amplifier processes the electrical signal and the reference signal formed in sequence, and generates m×2np second harmonic signals in sequence;

[0069] S7: The host computer processes the m×2np second harmonic signals generated sequentially to obtain the multi-dimensional combustion gas temperature and multi-component concentration.

[0070] In step S01, the control signal output by the signal generator is a modulation signal, and the reference signal output by the signal generator is a sinusoidal signal. The number of laser controllers is consistent with the number of lasers. If there are m lasers, there are also m laser controllers. One laser controller is electrically connected to one laser, and one laser controller controls one laser.

[0071] In step S6', the phase-locked amplifier processes not only the electrical signals formed in sequence but also the reference signals, and the obtained m×2np second harmonic signals are more accurate, making the multi-dimensional combustion gas temperature and multi-component concentration finally inverted more precise.

[0072] See also Figure 4 The third embodiment of the present invention also provides a method for measuring the temperature and multi-component concentration of multi-dimensional combustion gas in a furnace, the method comprising the following steps:

[0073] S1: The laser emits m first lasers, wherein 1≤m≤M, and M is the number of gas components to be measured; the wavelengths of the m first lasers respectively cover the molecular absorption spectral line ranges of the gas components to be measured;

[0074] S2: The optical switch couples the m first lasers into one laser and controls each of the m first lasers to output alternately according to a preset timing;

[0075] S3: The beam splitter divides each of the m first lasers output alternately in a preset time sequence into 2np lasers, where n and p are both positive integers;

[0076] Step S31: the fiber collimator calibrates each of the 2np lasers into a parallel laser in a time sequence;

[0077] S4: 2np lasers pass through the combustion gas, and the 2np lasers form a p-layer n×n optical path grid. Each component in the gas to be measured absorbs the first laser with the corresponding central wavelength; the m first lasers that are not completely absorbed pass through the combustion gas in sequence, and each first laser forms a 2np second laser.

[0078] S5: the photoelectric converter performs photoelectric conversion on the m types of 2np second lasers in a time sequence, and each 2np second laser forms 2np electrical signals;

[0079] S6: The lock-in amplifier processes the electrical signal formed in sequence in time, and generates m×2np second harmonic signals in sequence in time;

[0080] S7: The host computer processes the m×2np second harmonic signals generated sequentially to obtain the multi-dimensional combustion gas temperature and multi-component concentration.

[0081] In step S31, the fiber collimator calibrates each of the 2np lasers into a parallel laser in a time sequence, so that the second laser that subsequently passes through the combustion gas is more concentrated and not easily dispersed, which is more conducive to the photoelectric converter to perform photoelectric conversion, and further makes the multi-dimensional combustion gas temperature and multi-component concentration that are finally inverted more accurate. It can be understood that the photoelectric converter includes 2np and the fiber collimator also includes 2np, and the center of each fiber collimator and the center of each photoelectric converter are located on the same axis, that is, the laser emitted by the fiber collimator can be received by the photoelectric converter.

[0082] See also Figure 5 The fourth embodiment of the present invention also provides a method for measuring the temperature and multi-component concentration of multi-dimensional combustion gas in a furnace, the method comprising the following steps:

[0083] S1: The laser emits m first lasers, wherein 1≤m≤M, and M is the number of gas components to be measured; the wavelengths of the m first lasers respectively cover the molecular absorption spectral line ranges of the gas components to be measured;

[0084] S2: The optical switch couples the m first lasers into one laser and controls each of the m first lasers to output alternately according to a preset timing;

[0085] S3: The beam splitter divides each of the m first lasers output alternately in a preset time sequence into 2np lasers, where n and p are both positive integers;

[0086] S4: 2np lasers pass through the combustion gas, and the 2np lasers form a p-layer n×n optical path grid. Each component in the gas to be measured absorbs the first laser with the corresponding central wavelength; the m first lasers that are not completely absorbed pass through the combustion gas in sequence, and each first laser forms a 2np second laser.

[0087] S5: the photoelectric converter performs photoelectric conversion on the m types of 2np second lasers in a time sequence, and each 2np second laser forms 2np electrical signals;

[0088] S51: the acquisition card acquires the electrical signals generated by the photoelectric conversion of the m types of 2np second lasers in a time sequence and converts them into digital signals for transmission to the lock-in amplifier;

[0089] S6”: The lock-in amplifier processes the digital signal formed in sequence, and generates m×2np second harmonic signals in sequence;

[0090] S7: The host computer processes the m×2np second harmonic signals generated sequentially to obtain the multi-dimensional combustion gas temperature and multi-component concentration.

[0091] In step S51, the acquisition card is a capture device that captures external photoelectric, audio and other analog signals and digitizes them into a computer for digital processing. It mainly uses image acquisition cards, audio acquisition cards (such as sound cards), data acquisition cards, etc. The acquisition card collects the electrical signals formed by photoelectric conversion, converts them into digital signals, and transmits them to the lock-in amplifier, thereby improving the operating speed of the lock-in amplifier.

[0092] See also Figure 6 The fifth embodiment of the present invention provides a furnace multi-dimensional combustion gas temperature and multi-component concentration measurement system, which can measure the combustion gas using the furnace multi-dimensional combustion gas temperature and multi-component concentration measurement method described in any of the above embodiments. The furnace multi-dimensional combustion gas temperature and multi-component concentration measurement system 1 includes a host computer 10, a signal generator 11, a laser controller 12, a laser 13, an optical switch 14, a beam splitter 15, a fiber collimator 16, a photoelectric converter 17, an acquisition card 18 and a lock-in amplifier 19.

[0093] The signal generator 11 is electrically connected to the host computer 10, and is also electrically connected to the laser controller 12. The signal generator 11 is used to output a control signal to the laser controller 12 so that the laser controller 12 controls the laser 13 to emit laser light. The signal generator 11 also sends a reference signal to the lock-in amplifier 19. The control signal output by the signal generator 11 is a modulation signal, and the reference signal sent by the signal generator 11 is a sinusoidal signal.

[0094] The laser controller 12 is electrically connected to the host computer 10 through the signal generator 11. The laser controller 12 is also electrically connected to the laser 13. The laser controller 12 is used to control the laser 13 to emit a first laser. The number of laser controllers 12 is consistent with the number of lasers 13. If there are m lasers 13, there are also m laser controllers 12. One laser controller 12 is electrically connected to one laser 13, and one laser controller 12 controls one laser 13. In this embodiment, m=3, that is, the laser controller 12 includes a first laser controller 121, a second laser controller 122 and a third laser controller 123. The three laser controllers are all electrically connected to the signal generator 12.

[0095] The laser 13 is used to emit m kinds of first lasers, wherein 1≤m≤M, and M is the number of gas components to be measured; the wavelength bands of the m kinds of first lasers respectively cover the molecular absorption spectrum ranges of the gas components to be measured; the number of lasers 13 is consistent with the number of first lasers. Preferably, the laser 13 uses a DFB laser (Distributed Feedback Laser). The laser 13 includes m lasers, and each laser 13 emits a first laser. In this embodiment, m=3, the laser 13 includes a first laser 131, a second laser 132, and a third laser 133, the first laser 131 is electrically connected to the first laser controller 121, the second laser 132 is electrically connected to the second laser controller 122, the third laser 133 is electrically connected to the third laser controller 123, and the three lasers are all connected to the optical switch 14. In this embodiment, the gas components to be measured include H2O, CO, CO2 and NO; corresponding to H2O, the central wavelength range of the first laser is 1393.8nm~1401.8nm, preferably 1397.8nm, to obtain a wavelength of 7153.75cm -1 and 7154.35cm -1 Corresponding to CO and CO2, the central wavelength range of the first laser is 1575nm~1563nm, preferably 1759nm, to obtain 6338.59cm -1 The CO absorption line at 6337.99 cm -1 corresponding to NO, the central wavelength range of the first laser is 5259nm ~ 5267nm, preferably 5263nm, to obtain 1900.07cm -1 NO absorption line at .

[0096] The optical switch 14 is connected to the laser 13, and the optical switch 14 is also electrically connected to the host computer 10. The optical switch 14 is used to couple the m first lasers into one laser, and control each of the m first lasers to output alternately according to a preset timing. When the optical switch 14 is connected to the laser 13, an optical fiber connection is used, preferably a single-mode optical fiber connection. The central glass core of a single-mode optical fiber is very thin, and the core diameter is generally 9 or 10 μm. It can only transmit one mode of optical fiber, and its inter-mode dispersion is very small. The use of a single-mode optical fiber further increases the accuracy of the measurement.

[0097] The optical splitter 15 is connected to the optical switch 14, and the optical splitter 15 divides each of the m first lasers output alternately according to a preset timing into 2np lasers, where n and p are both positive integers. When the optical splitter 15 is connected to the optical switch, an optical fiber connection is used, preferably a single-mode optical fiber connection.

[0098] The optical fiber collimator 16 is connected to the optical splitter 15, and the optical fiber collimator 16 is used to correct each of the 2np lasers into a parallel laser in sequence. The 2np lasers pass through the combustion gas, and the 2np lasers form a p-layer n×n optical path grid. Each component in the gas to be measured absorbs the first laser with the corresponding central wavelength; the m first lasers that are not completely absorbed pass through the combustion gas in sequence, and each first laser forms a 2np second laser; when the optical fiber collimator 16 and the optical splitter 15 are connected, optical fiber connection is adopted, preferably single-mode optical fiber connection.

[0099] The photoelectric converter 17 is used to perform photoelectric conversion on m types of 2np second lasers in a time sequence, and each 2np second lasers forms 2np electrical signals.

[0100] The acquisition card 18 is electrically connected to the photoelectric converter 17. The acquisition card 18 collects the electrical signals formed by the photoelectric conversion of the m types of 2np second lasers in a time sequence and converts them into digital signals for transmission to the lock-in amplifier 19.

[0101] The phase-locked amplifier 19 is electrically connected to the acquisition card 18 and is also electrically connected to the host computer 10. The phase-locked amplifier 19 is used to process the m×2np digital signals and reference signals formed in sequence to generate m×2np second harmonic signals in sequence.

[0102] The host computer 10 is used to process the m×2np second harmonic signals generated in sequence to obtain the multi-dimensional combustion gas temperature and multi-component concentration. The type of the host computer 10 is not limited, such as the host computer 10 can be a computer or an industrial computer. The host computer is also used to control the operation of other devices, such as the operation of the optical switch 14.

[0103] Preferably, the gas component to be measured includes H2O, and the gas component to be measured further includes at least one of CO, CO2 and NO, and the temperature of the gas to be measured is inverted using the double absorption spectrum of H2O.

[0104] When in use, the host computer 10 controls the signal generator 11 to send a control signal to the laser controller 12. The host computer 10 also controls the signal generator 11 to send a reference signal to the phase-locked amplifier 19. The laser controller 12 controls the laser 13 to emit m kinds of first lasers according to the control signal. The host computer 10 controls the optical switch 14 to output each of the m kinds of first lasers alternately according to a preset timing. The optical splitter 15 divides each of the m kinds of first lasers alternately output according to the preset timing into 2np lasers. The optical fiber collimator 16 is used to correct each of the 2np lasers into a parallel laser according to the timing. The 2np lasers include a first part of n lasers and a second part of n lasers. The lasers in the first part of n lasers are parallel to each other, and the lasers in the second part of n lasers are parallel to each other; the n lasers in the first part and the n lasers in the second part are perpendicular to each other, and the 2np lasers are all in the same In one plane, 2np lasers pass through the combustion gas, and the 2np lasers form an n×n optical path grid. Each component in the gas to be measured absorbs the first laser with the corresponding central wavelength; the m first lasers that are not completely absorbed pass through the combustion gas in sequence, and each first laser forms 2np second lasers. The photoelectric converter 17 performs photoelectric conversion on the m 2np second lasers in sequence, and each 2np second laser forms 2np electrical signals. The acquisition card 18 collects the electrical signals formed by the photoelectric conversion of the m 2np second lasers in sequence and converts them into digital signals for transmission to the lock-in amplifier 19. The lock-in amplifier 19 processes the m×2np digital signals and the reference signal formed in sequence, and generates m×2np second harmonic signals in sequence. The host computer 10 processes the m×2np second harmonic signals generated in sequence to obtain the multi-dimensional combustion gas temperature and multi-component concentration.

[0105] It can be understood that the contents of the system for measuring the temperature and multi-component concentration of multi-dimensional combustion gas in a furnace and the method for measuring the temperature and multi-component concentration of multi-dimensional combustion gas in a furnace can complement and illustrate each other.

[0106] The host computer, laser, optical switch, photoelectric converter, phase-locked amplifier and other components used in the multi-dimensional combustion gas temperature and multi-component concentration measurement system in the furnace can all be selected from components sold on the market. The optical switch technology and spectrometer technology are used to realize the simultaneous measurement of multiple combustion parameter fields, simplify the system structure, save system costs, and eliminate mutual interference between gases.

[0107] It is worth noting that in all the above embodiments, the various units and modules included are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be achieved; in addition, the specific names of the functional units are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of the present invention.

[0108] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for measuring the temperature and multi-component concentration of multi-dimensional combustion gas in a furnace, characterized in that: The method for measuring the temperature and multi-component concentration of multi-dimensional combustion gas in the furnace includes: The laser emits m kinds of first lasers, wherein 1≤m≤M, and M is the number of gas components to be measured; the wavelengths of the m kinds of first lasers respectively cover the molecular absorption spectrum ranges of the gas components to be measured; The optical switch couples the m first lasers into one laser and controls each of the m first lasers to be output alternately according to a preset timing sequence; The beam splitter divides each of the m first lasers alternately output according to a preset timing into 2np lasers, where n and p are both positive integers, and p≥2; 2np lasers pass through the combustion gas, and the 2np lasers form a p-layer n×n optical path grid. Each component in the gas to be measured absorbs the first laser with a central wavelength corresponding to it; m types of first lasers that are not completely absorbed pass through the combustion gas in time sequence, and each first laser forms a 2np second laser. The photoelectric converter performs photoelectric conversion on m types of 2np second lasers in a time sequence, and each 2np second laser forms 2np electrical signals; The lock-in amplifier processes the electrical signal formed in sequence in time, and generates m×2np second harmonic signals in sequence in time; The host computer processes the m×2np second harmonic signals generated in sequence to obtain the multi-dimensional combustion gas temperature and multi-component concentration; The lock-in amplifier processes the electrical signals sequentially formed in time sequence to generate m second harmonic signals sequentially in time sequence, and further comprises: The acquisition card collects the electrical signals formed by the photoelectric conversion of the m types of 2np second lasers in a time sequence and converts them into digital signals for transmission to the lock-in amplifier; The lock-in amplifier processes the digital signal formed in sequence and generates m×2np second harmonic signals in sequence; Wherein, the optical switch and the laser are connected by a single-mode optical fiber; the optical splitter and the optical switch are connected by a single-mode optical fiber.

2. The method for measuring the temperature and multi-component concentration of multi-dimensional combustion gas in a furnace according to claim 1, characterized in that: The combustion gas temperature is The concentration of the gas component to be measured is where A = ∫ v A v (v)dv = ∫ v -ln(I t / I0)dv = P·X·S(T)L = α v L, A is the integrated absorbance on the light path; A v is absorbance; I0 and I t are the incident light intensity and the transmitted light intensity respectively; P is the total pressure of the mixed gas; X is the concentration of the medium gas component; L is the transmission distance of the laser path in the medium gas; S is the absorption line intensity; T is the temperature; α v is the gas absorption coefficient; v is the light frequency; The spectral line intensity S(T) at temperature T is: S(T0) is the intensity of the spectrum line at the reference temperature T0; E is the value of the low-state energy level; h is the Planck constant; k is the Boltzmann constant; c is the speed of light; v0 is the center frequency of the absorption spectrum line; Q(T) is the partition function value at temperature T, expressed as Q(T)=z0+z1T+z2T 2 +z3T 3 , The ratio of different absorption line intensities is R: The integrated absorption rate of a single light path can be expressed as the sum of the contributions of all the grids that the light path passes through to the absorption: i is the ray number; j is the grid number; Lj represents the optical path through the jth grid; J is the total number of grids; a is the integrated absorption coefficient within the grid; k is the number of iterations; A i represents the integrated absorption rate of the i-th ray; β is the relaxation coefficient, L ij The optical path of the i-th ray passing through the j-th grid; The ratio of the absorption line intensities within the grid is R i for: R i =a v1,i / a v2,i 。 3. The method for measuring the temperature and multi-component concentration of multi-dimensional combustion gas in a furnace according to claim 1, characterized in that: The laser emits m first lasers, wherein 1≤m≤M, M is the number of gas components to be measured, and further includes: The signal generator outputs a control signal to the laser controller so that the laser controller controls the laser. The signal generator also sends a reference signal to the lock-in amplifier. The lock-in amplifier processes the electric signal and the reference signal formed in sequence in time, and generates m×2np second harmonic signals in sequence in time.

4. The method for measuring the temperature and multi-component concentration of multi-dimensional combustion gas in a furnace according to claim 1, characterized in that: After the optical splitter divides each of the m first lasers alternately outputted in a preset time sequence into 2np lasers, the method further includes: The fiber collimator calibrates each of the 2np lasers into a parallel laser in a time sequence.

5. The method for measuring the temperature and multi-component concentration of multi-dimensional combustion gas in a furnace according to claim 1, characterized in that: The beam splitter divides each of the m first lasers alternately output according to a preset timing into 2np lasers, wherein the 2np lasers include a first part of np lasers and a second part of np lasers, the lasers in the first part of np lasers are parallel to each other, and the lasers in the second part of np lasers are parallel to each other; the first part of np lasers and the second part of np lasers are perpendicular to each other.

6. The method for measuring the temperature and multi-component concentration of multi-dimensional combustion gas in a furnace according to claim 1, characterized in that: The temperature of the gas to be measured is inverted using a double absorption line gas; the concentration of the gas to be measured is inverted using a single / double absorption line gas.

7. A multi-dimensional combustion gas temperature and multi-component concentration measurement system in a furnace, characterized in that: The multi-dimensional combustion gas temperature and multi-component concentration measurement system in the furnace includes a host computer, a laser, an optical switch, a spectrometer, a photoelectric converter, a lock-in amplifier and an acquisition card; The laser is electrically connected to the host computer, and the laser emits m kinds of first lasers, wherein 1≤m≤M, and M is the number of gas components to be measured; the wavelengths of the m kinds of first lasers respectively cover the molecular absorption spectrum ranges of the gas components to be measured; The optical switch is connected to the laser, and is also electrically connected to the host computer. The optical switch couples the m first lasers into one laser, and controls each of the m first lasers to be output alternately according to a preset timing sequence; The optical splitter is connected to the optical switch, and the optical splitter splits each of the m first lasers output alternately in a preset time sequence into 2np lasers, where n and p are both positive integers, and p≥2; 2np lasers pass through the combustion gas, and the 2np lasers form a p-layer n×n optical path grid. Each component in the gas to be measured absorbs the first laser with a corresponding central wavelength; m types of first lasers that are not completely absorbed pass through the combustion gas in sequence, and each type of first laser forms a 2np second laser. The photoelectric converter is used to perform photoelectric conversion on m types of 2np second lasers in a time sequence, and each 2np second laser forms 2np electrical signals; The acquisition card is electrically connected to the photoelectric converter, and the acquisition card collects the electrical signals formed by the photoelectric conversion of the m types of 2np second lasers in a time sequence and converts them into digital signals for transmission to the lock-in amplifier; The lock-in amplifier is electrically connected to the acquisition card, and is also electrically connected to the host computer. The lock-in amplifier processes the digital signals formed in sequence, and generates m×2np second harmonic signals in sequence. The host computer is used to process the m×2np second harmonic signals generated sequentially to obtain multi-dimensional combustion gas temperature and multi-component concentration; Wherein, the optical switch and the laser are connected by a single-mode optical fiber; the optical splitter and the optical switch are connected by a single-mode optical fiber.

8. The multi-dimensional combustion gas temperature and multi-component concentration measurement system in a furnace as claimed in claim 7, characterized in that: The laser is a DFB laser, and the laser includes m lasers, each of which emits a first laser.

9. The multi-dimensional combustion gas temperature and multi-component concentration measurement system in a furnace as claimed in claim 7, characterized in that: The gas component to be measured includes H2O, and the gas component to be measured also includes at least one of CO, CO2 and NO, and the temperature of the gas to be measured is inverted using the double absorption spectrum of H2O; Corresponding to H2O, the central wavelength range of the first laser is 1393.8nm~1401.8nm; Corresponding to CO and CO2, the central wavelength range of the first laser is 1575nm~1563nm; Corresponding to NO, the central wavelength range of the first laser is 5259nm~5267nm.

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